show all users on a Catalyst Cisco switch
Q1. How do I list all user accounts?
From the enable prompt, run show run | i username
...
CORE01.PUB.DAL01#sh run | i user
username operator password 7 <someHashedPassword>
CORE01.PUB.DAL01#
Q2. How would I reset the password for a specific user?
Change the password from configuration mode
CORE01.PUB.DAL01#conf t
CORE01.PUB.DAL01(config)#username <someuser> password 0 <somepassword>
Syntax is slightly different for an ASA...
mpenning-fw(config)# user <someuser> password <somepassword>
local users in Ciso IOS are listed in the running-config with the "username".
For your switches type "show run | b username" and look at the users listed there.
For the ASA it's a little bit easier, just type "show run username".
If the users are not local (radius, etc.) then you'll need to look on that server for the user list.